Relay device for indicating if input digit lies within a predetermined range



Jan. 30, 1962 J. GILL ETAL RELAY DEVICE FOR INDICATING IF' INPUT DIGITLIES WITHIN A PREDETERMINED RANGE Filed Sept. 25, 1959 2 Sheets-Sheet lINVENTORS 7765/59 G/ L Jan. 30, 1962 1 G|i ETAL 3,019,416

RELAY DEVICE FOR INDICATING IF' INPUT DIGIT LIES WITHIN A PREDETERMINEDRANGE Filed sept. 23, 1959 2 Sheets-Sheet 2 ffy' 3,0 i 9,4 i t PatentedJan. 30, l 962 Filed Sept. 23, 1959, Ser. No. 841,885 anims. (el.340-149) This invention relates to the art of digital comparators andmore particularly to a comparator for determining whether a digitalinput is greater or less than a pre-set digital reference value.

It is among the objects of the invention to provide a unit of the abovetype which is relatively simple in construction and is not subject toerrors due to transient signals, and which will dependably determine ifa digital input signal is below or above a pre-set reference value andprovide an alarm if such undesired condition is present.

According to the invention, these objects are accomplished by thearrangements and combination of elements hereinafter described and moreparticularly recited in the claims.

In the accompanying drawings, in which is shown one of various possibleembodiments of the several 'features of the invention,

FIG. 1 is a circuit diagram of a comparator unit for one decade,

FIG. 2 is a View similar to FIG. 1 of a comparator unit for the seconddecade, and

FIG. 3 is a circuit diagram of means to actuate the equipment.

Referring now to the drawings, the digital comparator comprises aplurality of substantially identical comparator units lil, 10', one foreach decade.

As shown in FIG. 1, each comparator unit comprises a plurality of relaysR-tl, R-l to R-9 inclusive, one for each digit of a decade. The relaysform contact bank 11 and two coil banks 12 and 13, for high and lowalarm respectively.

The contact bank 11 has ten positions, 0, 1-9 inclusive, each with acontact arm C-(i to C-9, corresponding to the ten digits 0 to 9inclusive, each contact arm normally engaging a xed contact 14. Thecontact arm C and fixed contact 14 at each position are connectedrespectively to the positive side of an associated diode 15, 16, thenegative sides of the diodes being connected together, and to anassociated terminal T0 to T-9 respectively, to which the input to thecomparator is connected.

The input in the illustrative embodiment shown is designed to connectone of the terminals T-0 to T-9 to ground as set forth herein. This maybe accomplished in any suitable manner such as, for example, as is shownin FIG. 3.

Thus, a switch S is provided having a plurality of contacts 0-9respectively designed to be engaged by a contact arm C connected toground. Each of the contacts 0-9 is connected to one side of a coil ofan associated relay RL, theother `side of the coil being connected to asource of positive potential.

Each relay has a contact arm CA connected to an associated terminal T-l)to T-9 and normally engaging a fixed contact FC-1 connected to a sourceof positive potential and spaced from a fixed Contact FC-2 connected toground.

Thus. as the contact arm C is rotated, depending upon the value of theinput signal, the terminals T-tl to T9 will successively be connected toground.

The contact arm C of a preceding position is connected by a lead 17 tothe fixed contact 14 of the succeeding position, and the lixed contact14 of the first position associated with the digit 0 and the contact armC-9 of the tenth position associated with the digit 9 are connected toterminals 21, 22 respectively.

As the coil banks 12 and 13 are identical, only the former will bedescribed. Thus, bank 12, which is for the high alarm, has a coil 24 foreach of the ten positions of bank 11 and controlling the Contact arms Cthereof. One end of each of the coils 24 is connected by common lead 25to terminal 25. The other end of each coil is connected to the positiveside of a diode 27, the negative side of which is connected to aterminal 28 and to one side of a lamp 29, the other side of which isconnected to a source of positive potential.

The terminal 23 is associated with a terminal 31, the latter beingconnected to the positive side of a diode 32, the negative side of whichis connected through normally open switch 33 to ground. The terminals 28and 31 are adapted to be connected in any suitable manner as by a pluginpin in the manner to be hereinafter described.

Associated with high alarm bank 12 and low alarm bank 13 are alarm andtransfer relays RA and RT respectively, each of which has two coils 38,41 and 39, 42 and a contact arm 55, 57 respectively adapted to becontrolled by either of the associated coils. The contact arm S5 of thealarm relay RA is normally spaced from fixed contact 56 when coils 38,41 are not energized, and the contact arm 57 of the transfer relay RT isnormally engaging xed contact 58 and spaced from fixed contact 59 whencoils 39, 42 are not energized.

One end of each of the coils 38, 39, 41, 42 is connected to a terminal43, 44, 45 and 46 respectively. The other end of each coil is connectedto the positive side of a diode 47, the negative side of which isconnected to a terminal 48, 49, 51, 52 respectively.

Terminal 21 of bank 11 is connected by lead 53 to terminals 49 and 51 ofcoils 39 and 41 and terminal 22 is connected by lead 54 to terminals 48and 52 of coils 38 and 42.

Fixed contact 56 is connected by lead 61 to terminal 62, which isconnected to one side of alarm lamp 63, the other side of which isconnected through normally open switch 60 to positive. Contact arm 55 isconnected to terminal 64, which is connected by lead to terminal 66 towhich contact arm 57 is connected.

Fixed contact 58 is connected by lead 67 to terminal 68, which isconnected to ground, and fixed contact 59 is connected to terminal 69,which is connected by lead 71 to terminal 62 of the second comparatorunit 10 (FIG. 2) for the second decade.

In the operation of the equipment, it will be assumed for purposes ofillustration that there are only two decades and the alarm lamp 63 is toindicate if the digital ..9 value being checked is greater than 35 orless than 24 for a given point under test.

To this end connections are made between the terminals 23, 31 ofposition 3 in bank 12 of comparator unit 11i and of position 5 in bank12 of comparator unit 10 for the high alarm, and between the terminals28, 31 of position 2 in bank 13 of comparator unit 10 and of position 4in bank 13 of comparator unit 10' for the low alarm.

Assuming that the point under test has a digital value of 33 and thatthe terminals T-S and T-3 of comparator units and 10 are connected toground as a result of such value of 33, and that the remaining terminalsT are connected to a positive potential, if terminals 26 and 26 of highalarm banks 12 and 12 are now connected to a source of positivepotential, coils 24- of positions 3 and 5 of said banks of units 10 and10 will be readied for energization.

At this time, through the action of a programmer (not shown), terminals43, 44 and 43', 44' of units 10 and 10 are connected to a source ofpositive potential and the switches 33 and 33 of banks 12 and 12 areclosed.

Closing of switches 33 and 33 will complete a circuit through coils 24of positions 3 and 5 of banks 12 and 12. of units 1t? and 10 to move thecontacts C-3 and C-S of banks 11 and 11 away from their associated iixedcontacts.

In addition, a circuit will be completed through the lamps 29 ofpositions 3 and 5 of units 10 and 10 to illuminate the digits 3 and 5which is the selected reference value.

Terminal T-3 of unit 10 is connected to ground as previously described,due to the first digit of the point under test having a value of 3, andterminals 43, 44 to a source of positive potential. Hence, current willflow in two paths, from such terminals 43, 44 through coils 38, 39,diodes 47, terminals 48, 49, leads 54, 53 to terminals 22, 21, thencethrough the closed contacts C and 14 of the positions 9 to 4 inclusive,diode 16 to terminal T-3 and through the closed contacts C and 14 of thepositions 0, 1, 2, diode 15 to terminal T-3.

Hence, coils 38 and 39 will be energized and contact arms 5S, S7 will bemoved to engage fixed contacts 56 and 59 to connect lamp 63 to terminal69 and thence by lead 71 to terminal 62 of unit 10.

Thus, the control of the alarm lamp 63 has been transferred to unit 10',as the value of the first digit 3" of the point under test is equal tothe value of the digit 3 to which it has been compared.

The high alarm bank 12 of unit 10' has been set as previously describedso that position 5 has been selected as the reference for the seconddigit. Consequently, contact arm C-S of bank 12 is spaced from tixedcontact 14.

However, since the value of the second digit of the point under test is3, and since contacts C-5 and 14 are open, current will Iiow only frompositive terminal 44', through coil 39 and lead 53 to terminal 21' andthence through closed contacts C and 14 of positions 0, 1 and 2 of bank11', diode 15 of position4 3 to terminal T3.

The consequent energization of coil 39 will cause the associated contactarm 57 to engage fixed contact 59', breaking the circuit to ground, andin addition, since contacts 55', 56 are open there Will not be acomplete circuit to lamp 63.

Thereupon, the programmer (not shown) closes the switch 60 associatedwith lamp 63, but as no circuit is completed thereto it will not beenergized and no alarm will be given as is proper, since the point undertest does not exceed 35.

The programmer then cycles to connect terminals 26, 2.6 of low alarmbanks 13 and 13' of units 10 and 10 to a source of positive potential,and coils 24 of posi- 4 tions 2 and 4 of said banks of units 10 and 10will be readied for energization.

At this time, through the action of the programmer, terminals 45, 46 and45, 46 of units 10 and 10 are connected to a source of positivepotential and the Switches 33 and 33 of banks 13 and 13 are closed.

Closing of switches 33 and 33 will complete a circuit through coils 24of positions 2 and 4 of banks 13 and 13 of units 10 and 10 to move thecontacts C-2 and C-4 of banks 11 and 11 away from their associated fixedcontacts.

In addition, a circuit will be completed through the lamp 29 ofpositions 2 and 4 of units 10 and 10 to illuminate the digits 2 and 4,which is the selected reference value.

Terminal T-3 of unit 10 is connected to ground, as previously described,due to the first digit of the point under test having a value of 3 andterminals 45, 46 to a source of positive potential.

However, since contacts C-Z, 14 of position 2 of bank 11 of unit 10 areopen, current will iow only from positive terminal 46, coil 42, lead 54,terminal 22, closed contacts C and 14 of positions 9 to 4 inclusive,diode 16 of position 3 to terminal T-3 which is connected` to. ground.

The energizaton of coil 42 will. cause the associated contact arm 57 toengage fixed contact 59, but as the contact 55 remains spaced from fixedcontact 56, no circuit will be completed to the alarm lamp, which is thecondition desired when the value of the point under test, i.e. 33,exceeds the reference value set, i.e. 24.

Where the value of the point under test exceeds the reference value of35, i.e., if it has a value of`,say, 36, then terminals T-3 and T-6 ofbank 11 and 11 of units 10 and 10 will be connected to ground.

Since the value of the first digit of the point under test is equal tothat of the reference, control of the alarm lamp will be switched tounit 10', as previously described.

Since contacts C-S and 14 of bank 11' of unit 10- are open, current willow from positive terminal 43', coil 38, lead 54, terminal 22', closedcontacts C and 14 of positions 9 to 7 inclusive, diode 16 to terminalT-6 and ground. Hence, coil 38 will be energized and contact arm 55 willengage fixed contact 56. As contact 57 remains in engagement with fixedcontact 58, a circuit Will be completed from ground to terminal 62 andthence through lead 71 to terminal 69 of unit 10.

As contact arms 55, 57 of unit 1t) are engaging their fixed contacts 56,59, a circuit will be completed to alarm lamp 63, so that when switch 60is closed by the programmer, the alarm lamp will be illuminated.

Since at the same time the programmer is closing the switches 33 and 33associated with the high alarm bank 12, 12 of units 10 and 10', thelamps 29 associated with positions 3 and S will be illuminated so thatillumination of the alarm lamp 63 will indicate that the value of thereference of 35 has been exceeded.

Where the value of the point under test is less than the reference valueof 24, i.e., if it has a value of, say, 13, then terminals T-l and T-3of banks 11 and 11 of units 10 and 10 will be connected to ground.

Since the value of the rst digit of the point under test, i.e., 1, isless than that of the reference, i.e., 2, current will flow only frompositive terminal 45, coil 41, diode 47, lead 53 to terminal 21 andthence through closed contacts C and 14 of position 0, diode 15 toterminal T-1.

Energization of coil 41 will cause contact 55 controlled thereby toengage xed contact 56, and since contact 57 is engaging fixed contact 58connected to ground, a circuit will be completed to one side of the lamp63. Thus, when switch 60 is closed by the programmer, the alarm lampwill be illuminated.

Since at the same time the programmer is closing the switches 33, 33associated with the low alarm banks 13, 13 of units 10 and 10', thelamps 29 associated with positions 2 and 4 will be illuminated so thatillumination of the alarm lamp will indicate that the value of the pointunder test is less than the reference value.

Although the illustrative examples of the equipment have shown itsoperation where the value of the point under test was between the highand low reference values and was greater than the high and less than thelow reference values, it is of course to be understood that othercombinations could exist.

Thus, the point under test could be greater than the low and greaterthan the high reference values so that only the high alarm would begiven, or it could be less than the low and less than the high referencevalues so that only the low alarm would be given.

The operation of the equipment under such conditions would be readilyapparent to one skilled in the art.

It is also to be understood that any number of comparator units could beprovided depending upon the number of decades involved and the equipmentwould function in the manner previously described.

With the equipment above described, since only relays and diodes areutilized, transient signals will not cause errors in operation, and asthe relays are dependable in operation and capable of long repeated usewithout breakdown, the need for servicing is kept to a minimum.

As many changes could be made in the above constructions and manyapparently widely different embodiments of this invention could be madewithout departing from the scope of the claims, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

l. A digital comparator comprising a plurality of relays, each having apair of normally closed contacts and an associated coil controlling saidcontacts, means connecting said contacts in series, two control relays,one control relay comprising an alarm relay having a fixed contact and acontact arm normally spaced therefrom and a coil, and the other controlrelay comprising a transfer relay havingT a iixed contact and a contactarm normally engaging said tixed contact and a coil, an indicatorconnected to one of the contacts of said alarm relay, the other contactbeing connected to one of the contacts of said transfer relay, means toconnect a source of potential across the indicator and the other Contactof said transfer relay, means connecting the ends of said seriesconnected contacts to one end of the coils of each of said controlrelays respectively, means to apply a source of potential between eachof the contacts of :any one of said plurality of relays and one of theends of the coils of each of said control relays respectively, wherebytwo paths for current flow will be provided, one from each of thecontacts to which a source of potential is applied to an associatedcontrol relay coil, and means to energize the coil of one of saidplurality of relays to open the contacts thereof to break the circuit ofone of said paths of current to the associated control relay coil onlywhen the energized relay of said plurality is other than the relay tothe contacts of which a source of potential has been applied.

2. The combination set forth in claim 1 in which a second plurality ofrelays is provided, each having a pair of normally closed contacts andan associated coil controlling said contacts, means connecting saidcontacts in series, a second alarm relay having a pair of normally opencontacts and a coil, a second transfer relay having a pair of normallyclosed contacts and a coil, said lirst transfer relay having anadditional fixed contact, the Contact arm of said rst transfer relaybeing normally spaced from said additional fixed contact, meansconnecting said additional Contact to one of the contacts of said secondalarm relay, means connecting the other contact of said second i alarmrelay to one of the contacts of said transfer relay, means to connect asource of potential to the other contact of said second transfer relay,means connecting the ends of said series connected contacts to one endof the coils of said second alarm relay and second transfer relayrespectively, means to energize the coil of one of said plurality ofrelays to open the contacts thereof, and means to apply a source ofpotential to the contacts of at least one of said plurality of relaysand to the free ends of the coils of said second alarm relay and saidsecond transfer relay.

3. The combination set forth in claim 2 in which each pair of contactsof said first and second plurality of relays has a pair of diodesassociated therewith, one side of each of the diodes of each pair beingconnected to an associated contact and the other sides of the diodesbeing connected together, the source of potential being applied to theconnected sides of the pair of diodes.

4. The combination set forth in claim 2 in which each plurality ofrelays comprises ten relays.

5. The combination set forth in claim l in which one side of each of thecoils of said plurality of relays is connected together, the other sideof each of said coils being connected to a terminal, a second terminalis associated wih each of said rst terminals, means to connect saidsecond terminals and the connected sides of said coils to a source ofpotential, and the means to energize the coil of one of said relayscomprises a contact member engaging the associated pair of terminals.

6. The combination set forth in claim 5 in which a diode is connected inseries with each of said second terminals and a normally open switch isconnected in series with each of said diodes.

7. The combination set forth in claim 5 in which a diode is connected inseries between each of said coils and the first terminal.

8. The combination set forth in claim 5 in which a diode is connected inseries between each of said coils and the rst terminal, an indicator isconnected at one side between said diode and said first terminal, adiode is connected in series with each of said second terminals, anormally open switch is connected in series with each o-f said lastnamed diodes and means to apply a potential to the other side of saidindicator, said diodes and said potentials being selected and arrangedfor current flow through said coil and said indicator and through bothof said diodes in the same direction.

9. A digital comparator comprising a plurality of relays, each having apair of normally closed contacts and a pair of coils, said coils beingarranged in two banks, each coil independently controlling theassociated pair of contacts, means connecting said contacts in series,two control relays, one control relay comprising an alarm relay having atixed contact and a contact arm normally spaced therefrom and a coil,and the other control relay oomprising a transfer relay having a fixedcontact and a contact arm normally engaging said fixed Contact, anindicator connected to one of the contacts of said alarnL relay, theother contact being connected to one of the contacts of said transferrelay, means to connect a source of potential across the indicator andthe other contact of said transfer rela means connecting the ends ofsaid series connected contacts to one end of the coils of each of saidcontrol relays respectively, means to apply a source of potentialbetween each of the contacts of any one of said plurality of relays andone of the ends of the coils of each of said control relaysrespectively, whereby two paths for current ow will be provided, onefrom each of the contacts to which a source of potential is applied toan associated control relay coil, and means alternately to energize oneof the coils in each banl; to ope-n the contacts of the associated relayto break the circuit of one of said paths of current to the associatedcontrol relay coil only when the energized relay of said plurality isother than the relay to the contacts of which a source of potential hasbeen applied.

10. The combination set forth in claim 9 in which said plurality ofrelays comprises ten relays associated with the digits 0 to 9inclusve,lone of the contacts of the relay associated with the 0 digitis connected to one end of the transfer relay coil and one of thecontacts of the relay associated with the 9 digit is connected to oneend of the alarm relay coil.

References Cited in the le of this patent UNITED STATES PATENTS HerbatMar. 23, 1937 VerneauX Ian. 23, 1951 Parks Sept. 4, 1951 Merrill Sept.7, 1954 Cunningham July 15, 1958

